1. Field of the Invention
The invention is directed to a multi function control mechanism for a work vehicle which independently positions hydraulic control valves through the manipulation of a single control lever.
2. Description of the Prior Art
In operating work vehicles such as crawler dozers, the operator controls a plurality of work operations through manipulating various control levers that control the positioning of hydraulic control valves and thereby the flow of hydraulic fluid to hydraulic cylinders of a work implement. It is desirable to control a number of work operations from a single control lever. Typically three function control levers have a T-bar shaped control handle that can be moved through orthogonal control arcs to operate the first two functions and twisted to control a third function. It is desirable that the control lever be manipulated to operate each of the functions independently or in unison with the other functions.
Such three function control levers are used on crawler dozers manufactured and marketed by the assignee of the present application, for controlling the position of the working blade. These control levers are operatively coupled to the supporting frame of the dozer by a series of universal joints and/or ball joints. See U.S. Pat. Nos. 3,131,574, 3,388,609 and 4,938,091 all of which are assigned to the assignee of the present patent application. U.S. Pat. Nos. 4,536,055, 4,978,273 and 5,429,037 disclose other examples of three function control mechanisms.